Lake Powell is a storage facility for the Upper Basin states of the Colorado River Compact (Colorado, Utah, Wyoming, and New Mexico). The Compact specifies that the Upper Basin states are to provide a minimum annual flow of 7,500,000 acre feet (9.3 km3) to the Lower Basin states (Arizona, Nevada, and California).

Contents

History[edit]

In the 1940s and early 1950s, the U.S. Bureau of Reclamation planned to construct a series of Colorado River dams in the rugged Colorado Plateau province of Colorado, Utah, and Arizona. Glen Canyon Dam was born of a controversial damsite the Bureau selected in Echo Park, in what is now Dinosaur National Monument in Colorado. A small but politically effective group of objectors led by David Brower of the Sierra Club succeeded in defeating the Bureau's bid, citing Echo Park's natural and scenic qualities as too valuable to submerge. By agreeing to a relocated damsite near Lee's Ferry between Glen and Grand Canyons, however, Brower did not realize what he had gambled away. At the time, Brower had not actually been to Glen Canyon. When he later saw Glen Canyon on a river trip, Brower discovered that it had the kind of scenic, cultural, and wilderness qualities often associated with America's national parks.[2] Over 80 side canyons in the colorful Navajo Sandstone contained clear streams, abundant wildlife, arches, natural bridges, and numerous Native American archeological sites. By then, however, it was too late to stop the Bureau and its commissioner Floyd Dominy from building Glen Canyon Dam. Dominy was a firm believer in putting the river to human use, once saying "Now I admit that nature can't improve upon man. We're probably the supreme being."[citation needed] Brower believed the river should remain free, and would forever after consider the loss of Glen Canyon his life's ultimate disappointment.[citation needed]

Glen Canyon Dam in Page, Arizona

Construction on Glen Canyon Dam began with a demolition blast keyed by the push of a button by President Dwight D. Eisenhower at his desk in the Oval Office on October 1, 1956. The first blast started clearing tunnels for water diversion. On February 11, 1959, water was diverted through the tunnels so dam construction could begin. Later that year, the bridge was completed, allowing trucks to deliver equipment and materials for the dam, and also for the new town of Page, Arizona.

Concrete placement started around the clock on June 17, 1960. The last bucket of concrete was poured on September 13, 1963. Over 5 million cubic yards (4,000,000 m³) of concrete make up Glen Canyon Dam. The Dam is 710 feet (216 m) high, with the surface elevation of the water at full pool being approximately 3700 feet (1100 m). Construction of the Dam cost $155 million, and 18 lives were lost in the process. From 1970 to 1980, turbines and generators were installed for hydroelectricity. On September 22, 1966, Glen Canyon Dam was dedicated by Lady Bird Johnson.

Lake Powell

Upon completion of Glen Canyon Dam on September 13, 1963, the Colorado River began to back up, no longer being diverted through the tunnels. The newly flooded Glen Canyon formed Lake Powell. It took 11 years for the lake to rise to the high-water mark, on June 22, 1980. Since then the lake level has fluctuated considerably depending on the seasonal snow runoff from the mountains.[3][4][5]

Colorado River flows have been below average since the year 2000, leading to lower lake levels. In the winter of 2005 (before the spring run-off) the lake reached its lowest level since filling, an elevation of 3,550 feet (1,080 m) above sea level, which was approximately 150 feet (46 m) below full pool (elevation 3700'). Since 2005 the lake level has risen 78 feet (24 m), to a high elevation of 3,628 feet (1,106 m) above sea level in spring/early summer 2008. However, 2011 saw the third largest June and the second largest July runoff since the closure of Glen Canyon Dam, and the water level peaked at nearly 3,661 feet (1,116 m) on July 30.

Water year 2012 (which started October 1, 2011) has been the extreme opposite of 2011. The huge runoff in 2011 raised the lake over 50 feet from May to July.

In water year 2013, Lake Powell experienced a second consecutive year of low inflows, with only a brief period of refill in late May and June pushing the lake level up 5 feet before outflows again began outpacing inflows.

In 2014, despite near-average runoff, the Bureau of Reclamation reduced for the first time the annual release from Lake Powell to Lake Mead, from 8.23 to 7.48 million acre-feet, in order to help recover levels at Lake Powell for power generation. This resulted in Lake Mead declining to the lowest level on record since the 1930s.

The more recent (Jurassic Period) formations include Kayenta Sandstone, which produces the trademark blue-black "desert varnish" that streaks down many walls of the canyons. Above this is Navajo Sandstone, the result of more compressed sand dunes. Many of the arches, including Rainbow Bridge, lie at this transition point. This period also includes light yellow Entrada Formations, and the dark brown, almost purple Carmel Formation. These latter two can be seen on the tops of mesas around Wahweap, and the crown of Castle Rock and Tower Butte. Above these layers lie the Straight Cliffs Sandstone and conglomerate shales that make up the Kaiparowits Plateau and San Rafael Swell to the north of the lake.

The confluences of the Escalante, Dirty Devil and San Juan Rivers with the Colorado lie within Lake Powell. The slower flow of the San Juan river has produced goosenecks where 5 miles (8.0 km) of river are contained within 1-mile (1.6 km) on a straight line.

Environmental impacts[edit]

More information on Environmental impacts can be found in the Glen Canyon Dam article.

Landmarks[edit]

Rainbow Bridge

Glen Canyon Dam, the dam that keeps Lake Powell the way it is today. (location: Lake Powell's Arizona part)

Hite Crossing Bridge, the only bridge spanning Lake Powell. Although the bridge informally marks the upstream limit of the lake, when the lake is at its normal high water elevation, backwater can stretch up to 30 miles (48 km) upstream into Cataract Canyon

Popular culture[edit]

Lake Powell has been a shooting location for 45 television series and films,[6] including:

Features[edit]

Area features, click to enlarge

The lake's main body stretches up Glen Canyon, but has also filled many (over 90) side canyons. The lake also stretches up the Escalante River and San Juan River where they merge into the main Colorado River. This provides access to many natural geographic points of interest as well as some remnants of the Anasazi culture.

Glen Canyon National Recreation Area draws more than two million visitors annually. Recreational activities include boating, fishing, waterskiing, jet-skiing, and hiking. Prepared campgrounds can be found at each marina, but many visitors choose to rent a houseboat or bring their own camping equipment, find a secluded spot somewhere in the canyons, and make their own camp (there are no restrictions on where visitors can stay).

Currently most Marinas on the lake don't have Automatic Identification System monitoring stations that transmit boat positions to the AIS websites for the boating community. A substantial number of vessels on the lake do not have AIS transponders as there currently are no mandatory requirements for AIS usage for this body of water. Extra precautions must be taken with respect to boating safety, as the fractal nature of the lake's hydrologic surface area can allow vessels with limited charting equipment to become easily lost.

The burying of human (and pet) waste in Glen Canyon National Recreation Area is prohibited. Anyone who camps further than a quarter of a mile from a marina, however, must bring a portable toilet. Pet waste must also be packed out.

Introduced species[edit]

Zebra and Quagga mussels at Lake Powell[edit]

The mussels were initially brought to the United States through the ballast water of ships entering the Great Lakes. These aquatic invaders soon spread to many bodies of water in the Eastern United States and have even made their way to the western United States. In January 2008,[8][9] Zebra mussels have been detected in several reservoirs along the Colorado River system such as Lakes Mead, Mojave, and Havasu.

Zebra and Quagga mussels can be destructive to an ecosystem due to competition for resources with native species.[1] The filtration of zooplankton by the mussels can negatively impact the feeding for some species of fish. Zebra and quagga mussels can attach to hard surfaces and build layers on underwater structures. The mussels are known to clog pipes including those in hydroelectric power systems, thus becoming a costly and time-consuming problem for water managers in the West.

Control policies have recently been introduced to alleviate the hydroelectric problems as well as ecological problems faced by Western infestation. Beginning in 1999 Lake Powell began to visually monitor for the mussels.

In 2001 hot water boat decontamination sites were established at Wahweap, Bullfrog, and Halls Crossing marinas. In January 2007, zebra mussels were detected in Lake Mead and new action plans were announced to prevent the spread of mussels to Lake Powell. In August 2007, preliminary testing was positive for zebra or quagga larvae in Lake Powell. These tests were deemed false positives, but adult quagga mussels were found in 2013.

In August 2010, Lake Powell was declared mussel free. Lake Powell introduced a mandatory boat inspection for each watercraft entering the reservoir beginning in June 2009. Effective June 29, 2009, every vessel entering Lake Powell must have a mussel certificate, although boat owners were allowed to self-certify. These measures were intended to help prevent vessels from transporting Zebra mussels into Lake Powell.

Despite these measures, quagga mussel DNA was detected in 2012 and live mussels were found at a number of sites in Spring and Summer 2013. As of June 2013 the NPS was attempting a diver based eradication program to find and remove mussels before the lake becomes infested.